Eccentric drive for sewing machines



Aug. 24, 1954 A. H. ERIKSSON 2,687,104

ECCENTRIC DRIVE FOR SEWING MACHINES Filed May 9, 1950 2 Sheets-Sheet 1Wan:

I12 V2f0f ,4 226572 H. EH/rsswz Aug. 24, 1954 A. H. ERIKSSON 2,637,104

ECCENTRIC DRIVE FOR SEWING MACHINES Filed May 9, 1950 2 Sheets-Sheet 2 IInven'or A ZZan EFLIASJOH A By Z I 1 ZZys. I

Patented Aug 24, 1954 ECCENTRIC DRIVE FOR SEWING MACHINES Allan HermanEriksson, Huskvarna, Sweden, as-

signor to Husqvarna Vapenfabriks Aktiebolag, Huskvarna, Sweden, aSwedish corporation Application May 9, 1950, Serial No. 160,864

The present invention refers to an arrangement in sewing machinesprovided with a feeding mechanism, which is adjustable to vary thelength of stitch and to reverse the feeding direction.

The main object of the invention is to provide an eccentric drivingmeans which is particularly well suited to the control of a sewingmachine having a feeding mechanism of the above mentioned type.

A further object of the invention is to provide an adjustable eccentricdriving means which can be easily adjusted as to the magnitude as wellas the extent of the eccentricity, and as a result can be utilized in asewing machine to vary the stitch length and the direction of the feedfrom forward to back drive andvice versa. A still further object oftheinvention is to provide control means for an adjustable eccentricdriving mechanism of a simple and compact design.

With these and other objects in. view the invention consists of themechanism defined in the claims and specified more in detail by way ofexample in the following description, reference being had to theaccompanying drawings in which Fig. 1 is a vertical elevation of asewing machine, certain parts being illustrated in section along the armshaft of the machine,

Fig. 2 is a transverse section taken on the broken line II-II in Fig. 1,

Fig. 3 is a part bottom view as indicated by the line IIIIII in Fig. 1and illustrates a portion of the arm of the sewing machine and a detail,

Fig. 4 is a section on line IV -IV in Fig. 1, and

Fig. 5 is a section on line VV in Fig. 1.

Fig. 6 is an end view of the eccentric proper.

Fig. 7 is a cross section of a detail partly in plan.

The sewing machine illustrated in the drawing comprises the conventionalwork table I, the hollow standard 2 carried by the table I, the hollowarm 3 forming an integral portion of the standard 2, and the drivingmechanism for the stitch form.- ing means and the feeding device for thework, only such parts of the driving mechanism being shown as arenecessary for the understanding of the invention. The drive is obtainedin the conventional manner through a belt pulley 4 connected to a rotaryarm shaft 5 extending longi tudinally in the arm 3.

Secured on the arm shaft 5, through which, inter alia, the needle bar 6of the sewing machine receives its movement, are two eccentrics 1 and 8,which through the intermediary of eccentric 6 Claims. (Cl. 112210) rods9 and I 0, levers l I and I2, and rocking shafts M and I5 respectively(Fig. 2) impart to the feeder l5 pertaining to the work feedingmechanism of the sewing machine, the necessary longitudinal and verticalmovement. The longitudinal movement must permit of being readily variedto provide for varying stitch lengths and a varying feeding direction,which is facilitated through the eccentric drive in consideration.

According to the invention, the eccentric drive comprises an eccentric 8having an outer bearing surface 1'! paralleling the shaft 5, the strapit of the eccentric rod Ill being mounted on said bearing surface. Theeccentric 8 also has an inner member is, which here takes the form of acylinder, the envelope surface of which forms a bearing surface carryingthe eccentric 8. cylinder is disposed obliquely in such manner that itsgeometrical axis intersects the axis of the arm shaft 5 at a certainangle. The inner member 19 is displaceable on the arm shaft withoutbeing rotatable relatively to the latter, while the eccentric l, whichalso is non-rotatable relatively to the shaft, takes an unchanged axialposition. By axially displacing the member 19 it is possible to movebearing surface I! to alter the eccentric radius of the bearing surfacell relatively to the shaft 5, so that the length of stroke of theeccentric rod I0 is changed with a change of the longitudinal movementof the feeder It for the fabric in consequence thereto.

Instead of displacing the member l9 relatively to the shaft, adisplacement of the eccentric is conceivable in connection with acorresponding alteration of the remainder of the arrangement, thesubstantial feature residing in a mutual axial adjustment of theseparts. Also, it is not necessary that the member l9 be constituted by acylinder; it may just as well consist of an arbitrary suitableparallelopipedon.

The arrangements required for the operation of the adjustment of themember 19 and to prevent turning of said member and the eccentricelement 3 relatively to the shaft 5 may be of any suitable kind.However, the details shown in the drawings are particularly well suitedin connection with driving means for sewing machines.

The contrivance in consideration is devised so that the surface IT, onwhich the strap l8 of the eccentric rod in is mounted, is concentric tothe shaft 5, when during the axial adjustment of the member l9 saidmember takes a middle position in which no longitudinal movement of thefeeder i6 is obtained. From said middle position, the member [9 may thusbe displaced in the one or the other direction, and in the example shownThe an equal change of the length of stroke of the eccentric rod will beobtained at an equal displacement of the member I9 in either direction,whereas the position of the eccentric radius is reversed by 180, whenmember I9 is displaced from a position on one side of the middleposition to the other side thereof.

In order to render possible the axial adjustment of the eccentric memberI9 in the arrangement shown, said member is connected through a flangecoupling, which may entrain the member I9 at an axial adjustment on theshaft but does not prevent its rotation with the latter, to a sleevewhich is rotatable and displaceable on the shaft. The flange couplingcomprises a flange 2| formed at a tubular portion 22 at member I9 and ofa flanged sleeve 23 secured to sleeve 23 by bolts 24, the flanged sleeve23 and flange 2i engaging one another slidably. Sleeve 23 has a slot 25,with which a plate 27 on a stop screw 23 screwed into the wall of thearm of the sewing machine may be caused to operate. The stop screw andthe slot permit rotation of the sleeve 29 through a certain angle on theshaft 5, which angle is reduced, according as the stop screw is screwedin, and is equal to zero, when the plate is entirely within the slot. Aspring 28 thrust onto sleeve 20 tends to keep said sleeve with one edgeof the slot against the plane bottom surface 29 of the plate 21, so thata certain length of stitch is obtained in the normal sewing or feedingdirection from the operator. If the sleeve 20 is turned so that theopposite edge of the slot 25 is caused to touch the bottom surface 29,the same length of stitch is obtained in the opposite feeding direction.Provided on the lower side of the arm of the sewing machine is a pin 30engaging an obliquely extending slot 3| in the sleeve 20, said sleevehaving also an operating lever 32 secured thereon, which projectsthrough an opening 33 on the lower side of the sewing machine arm 3.

The eccentric 8 is non-rotatably arranged on the shaft 5, which featureis ensured for instance by the fact that the eccentric 8 has a ridge i4engaging a recess 35 in a sleeve 36 secured to the shaft 5 by a screw31, said sleeve 36 having also the eccentric 1 formed thereon. The innermember I9 is prevented from rotating relatively to the shaft by the factthat a projection 38 thereon engages the recess 35, which is of such anaxial extension as to permit the axial displacement of the member I9 ata variation of the eccentricity. By means of the ridge 34 and a ring 39slidably bearing on the strap I8 of the eccentric rod I 0 the member 8is mounted so that it can move parallel only with a plane in thetransverse direction of the shaft. A retaining ring 40 is secured toeccentric 8 by bolts 4! and contributes to keep said eccentric and strapl8 in correct position relatively to one another. The sleeve 36 has aradial flange 42 transversed by an extension 43 of recess 35, andlaterally of said extension the ring 39 is secured to the flange 42 byscrews 44. Thus ridge 34, ring 39 and screws 44 couple the eccentric 8and the sleeve 36 to one another in a manner permitting radial movementof the eccentric relatively to the sleeve but not mutual rotationthereof.

With respect to the mode of operation of the arrangement the followingmight also be pointed out: As stated, the operating arm is normallyretained by the spring 28 in an outer position with one edge of the slot25 bearing on the plate that it is moved into a middle position, inwhich the plate 2'! is located opposite the slot 25. Now, if theoperating lever 32 is actuated so that the sleeve 20 is caused onaccount of the pin 30 and the oblique slot 3| to move the eccentricmember I3 from its middle position in the direction of the arrow 40 inFig. 1 as far as is permitted by the stop screw 26 and the slot 25, amaximum eccentricity is obtained for the eccentric drive in the feedingof the work in one direction, for instance in the direction from theoperator. Again, if the operating lever 32 is moved in the oppositedirection, as far as is permitted by the stop screw, the member I9 isdisplaced in a direction opposed to that of the arrow 49. The sameeccentricity is now obtained, but the radius of the eccentric isreversed with respect to its position by 180, and the feeding directionwill be the opposed, that is to say toward the operator. Between theindicated extreme positions the eontrivance may be adjusted by means ofthe operating lever 32 into arbitrary intermediate positions at acorresponding eccentricity and length of stitch.

The eccentric drive as described brings about a compact structure and iswell suited for sewing machines, in particular also sewing machinesrunning at a very high number of revolutions. While the control of thelength of stitch becomes simple, an easily effected change of thefeeding direction of the fabric is rendered possible at the same time.The eccentric driving means may be mounted on a shaft other than the armshaf for similar purposes.

What I claim is:

1. In a sewing machine having a rotary shaft in the arm of the standard,an eccentric driving means comprising a member mounted axiallydisplaceably on said shaft, said member having a surface extending at anangle to the axis of the shaft, an eccentric mounted on the shaft andcarried slidably by said surface and having an axial bearing surface, aneccentric strap mounted on said bearing surface, an eccentric rodconnected with said eccentric strap, means for guiding the eccentric inthe radial direction of the shaft, said guide means comprising a sleeveand releasable means to key said sleeve to the shaft in any peripheralposition thereon, operating means to displace said axially displaceablemember on the shaft relative to the eccentric to displace the eccentricradially and to vary the eccentricity thereby, said eccentric beingadjustable during operation, the means for the axial displacement ofsaid member on the shaft comprising the operating sleeve mounteddisplaceably and rotatably around the shaft and having a slot therein, aplate adjustable to limit the movement of the sleeve for a variableextent by contact in the slot, means to turn said sleeve on the shaft,and means to guide the sleeve to provide only a limited rotary movementbut also a limited axial displacement.

2. In a sewing machine having a rotary shaft in the arm of the standard,an eccentric driving means comprising a member mounted axiallydisplaceably on said shaft, said member having a surface extending at anangle to the axis of the shaft, an eccentric mounted on the shaft andcarried slidably by said surface and having an axial bearing surface, aneccentric strap mounted on said bearing surface, aneccentric rodconnected with said eccentric strap, means 27 of the stop screw 26, butit is assumed here for guiding the eccentric in the radial direction ofthe shaft, said guide means comprising a sleeve and releasable means tokey said sleeve to the shaft in any peripheral position thereon,operating means to displace said axially displaceable member on theshaft relative to the eccen tric to displace the eccentric radially andto vary the eccentricity thereby, said eccentric being adjustable duringoperation, the means for theaxial displacement of said member on theshaft comprising the operating sleeve mounted displaceably and rotatablyon the shaft and having an axial slot and an oblique slot, a stop memberengaging said axial slot to a variable extent to variably limit therotation thereof, and a guide pin in the sewing machine engaging saidoblique slot to cause axial displacement of said operating sleeve uponrotation thereof.

3. In a sewing machine having a rotary shaft in the arm of the standard,an eccentric driving means comprising a member mounted axiallydisplaceably on said shaft, said member having a surface extending at anangle to the axis of the shaft, an eccentric mounted on the shaft andcarried slidably by said surface and having an axial bearing surface, aneccentric strap mounted on said bearing surface, an eccentric rodconnected with said eccentric strap, means for guiding the eccentric inthe radial direction of the shaft, said guide means comprising a sleeveand releasable means tokey said sleeve to the shaft in any peripheralposition thereon, operating means to displace said axially displaceablemember on the shaft relative to the eccentric to displace the eccentricradially and to vary the eccentricity thereby, said eccentric beingadjustable during operation, the operating means comprising theoperating sleeve mounted around the shaft and having a slot therein, amanually adjustable stop device cooperating with and extending into theslot, and an operating member for displacing the operating sleeveaxially on the shaft between two end positions determined by said stopdevice in the cooperating slot.

4. In a sewing machine having a rotary shaft in the arm of the standard,an eccentric driving means comprising a member mounted axiallydisplaceably on said shaft, said member having a surface extending at anangle to the axis of the shaft, an eccentric mounted on the shaft andcarried slidably by said surface and having an axial bearing surface, aneccentric strap mounted on said bearing surface, an eccentric rodconnected with said eccentric strap, means for guiding the eccentric inthe radial direction of the shaft, said guide means comprising a sleeveand releasable means to key said sleeve to the shaft in any peripheralposition thereon, operating means to displace said axially displaceablemember on the shaft relative to the eccentric to displace the eccentricradially and to vary the eccentricity thereby, said eccentric beingadjustable during operation, the operating means comprising theoperating sleeve on the shaft and having a slot therein, a manuallyadjustable stop device cooperating with and extending into the slot, anoperating member for displacing the operating sleeve axially on theshaft between two end positions determined by said stop device in thecooperating slot, and a spring mounted around the sleeve to force saidsleeve in one of said end positions.

5. In a sewing machine according to claim 3, in which the operatingmember is in the form of a manually operable push lever extending in theproximity of the needle operating head of the machine.

6. In a sewing machine having a rotary shaft and a reciprocating workfeeding mechanism, an eccentric driving means comprising a membermounted axially displaceably on said shaft, said 1 member having asurface extending at an angle to the axis of the shaft, an eccentricmounted on the shaft and carried slidably by said surface and having anaxial bearing surface, means operated by said bearing surface fortransmitting motion from said eccentric to said feeding mechanism, meansfor guiding the eccentric in the radial direction of the shaft,operating means to displace said axially displaceable member on theshaft relative to the eccentric to displace the eccentric radially andto vary the eccentricity thereby, said eccentric being adjustable duringoperation between diametrically opposite positions corresponding toforward and backward feed, the operating means comprising an operatingsleeve mounted around the shaft, an abutment member movable in unisonwith said sleeve about a middle position corresponding to theeccentricity and the stitch length naught and carrying two abutmentscorresponding to forward feed and backward feed, a manually adjustablestop member extending into the path of said abutments for alternativecooperation therewith, a spring connected with said abutment member tokeep said stop member in engagement with the abutment corresponding toforward feed, and an operating member for displacing the operatingsleeve axially on the shaft between two end positions determined by saidstop member.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 540,843 Richards June 11, 1895 718,988 Dial et al Jan. 27,1903 2,577,705 Hoffmeister Dec. 4, 1951 FOREIGN PATENTS Number CountryDate 242,851 Germany Jan. 22, 1912

